Two-photon contributions to e+e-→ηγ and e+e-→η'γ

Motivated by recent BABAR measurements of the gamma(*)->gamma eta and gamma(*)->gamma eta(') transition form factors, we estimate two-photon exchange contributions to the corresponding cross sections. By using a phenomenological model, based on the vector meson dominance, it is argued that the expected contributions are small enough not to effect the BABAR results. As a by product we predict Br(eta(')->mu(+)mu(-))=(1.4 +/- 0.2)x10(-7). Our results might be useful also in high precision calculations of radiative corrections to the Dalitz decays of pseudoscalar mesons.